1. Field
This application relates to pulse generators and, more particularly, to pulse generators that may be used for electroperturbation of biological cells.
2. Description of Related Art
Ultra-short, high-field strength electronic pulses may be used in the electroperturbation of biological cells. The voltage induced across a cell membrane may depend on the pulse length and pulse amplitude. Pulses longer than ˜1 μs may charge the outer cell membrane and lead to opening pores, either temporarily or permanently. Permanent openings may result in cell death. Pulses much shorter than ˜1 μs can affect the cell interior without adversely affecting the outer cell membrane. Pulses lasting a few tens of nanoseconds and with a 2-10 MV/m amplitude may trigger apoptosis or programmed cell death.
Shorter and higher amplitude electronic pulses are useful for cell biology research to probe and manipulate intracellular structures such as nuclei and mitochondria.
Spark gap switched transmission lines have been used to generate ultra-short pulses. However, they may be physically large and have only a low repetition rate. They may also have only a relatively short lifetime, and provide erratic pulses with a large amount of jitter. The transmission line capacitance may also need to be charged rapidly in order to overvolt the spark gap to meet a fast rise time requirement.
Radio frequency MOSFET switched capacitors have also been used to generate ultra-short pulses. However, MOSFET switched capacitors may not be able to generate pulses that are narrower than 15-20 ns. This may be due to complications of MOSFET driving circuits and inherent limitations of many MOSFET devices.